1. Field of the Invention
The present invention relates to N-substituted-7-amino-5-hydroxy-3-oxoheptanoic acid derivatives and a method for producing the same. These novel compounds are useful as synthetic intermediates for preparing 3-hydroxy-3-methylglutaryl coenzyme A (abbreviated as HMG-CoA below) reductase inhibitors known as antilipemic agents, namely, trans-6-[2-substituted pyrrole-1-yl )alkyl]-4-hydroxypyran-2-one derivatives, for example, (2R) -trans-5-[(4-fluorophenyl)-2-(1-methylethyl)-N-4-diphenyl]-1-[2-tetrahydro -4-hydroxy-6-oxo-2H-pyran-2-yl)ethyl]-1H-pyrrol-3-carboxyamide.
2. Description of the Related Art
Lactone residues which are considered to be the active sites of HMG-CoA reductase inhibitors, trans-6-[2-(substituted pyrrole-1-yl)alkyl]-4-hydroxypyran-2-one derivatives, have been synthesized via a series of steps from esters of 6-(2-aminoethyl)-2,2-dimethyl-1,3-dioxane-4-acetic acid having the general formula (5): ##STR2## where R represents an alkyl group.
Furthermore, methods for producing these dioxane derivatives (5) which comprise reducing the cyano group in esters of 6-cyanomethyl-2,2-dimethyl-1,3-dioxane-4-acetic acid as a starting material, are disclosed in Japanese Patent Laid-Open No. 3-502798 corresponding to U.S. Pat. No. 5,003,080, Japanese Patent Laid-Open No. 6-502162 corresponding to U.S. Pat. No. 5,103,024, and U.S. Pat. No. 5,155,251.
However, these methods using cyanide compounds have raised safety concerns. Namely, toxic alkaline cyanide must be used for obtaining the cyanide compounds, and alcohol containing toxic ammonia gas must be employed to reduce the cyano group. Thus, these methods require complex equipment and are troublesome to carry out.